When an agitator is used in making a product, which initially has a low viscosity but which subsequently develops a higher viscosity, that product can provide a progressively-increasing resistance to the movement of that agitator. In Lents U.S. Pat. No. 3,108,449 for Machine For Making An Icy Product With Torque Sensitive Control, which was granted on Oct. 29, 1963, a rotatable agitator easily stirs a mixture of syrup and carbonated water until that mixture begins to freeze. The resulting increase in the viscosity of that mixture provides a progressively-increasing resistance to the rotation of that agitator within that mixture; and that progressively-increasing resistance to rotation causes a coupling element to shift out of its initial position. The shifting of that coupling element is sensed by a switch which de-energizes a refrigeration compressor to keep the mixture of syrup and carbonated water from becoming a solid frozen mass. As the temperature of that mixture subsequently increases, with a consequent decrease in the viscosity of that mixture, the coupling element will shift back toward its initial position, and thereby enable the switch to re-energize the refrigerant compressor.